Yes, it is one of the most popular sports in Japan.
Yes, it was the second most popular sport in the world when it was introduced in Japan
Baseball is a very popular sport in Japan
yes, not baseball.
Baseball is the most popular sport, NOT lawn bowls. I live in Japan and have never even heard of 'lawn bowls'. They also like wrestling.
The second most popular spectator sport is marathons, then ekiden which is a long distance relay race.
because kids love it
yes, the National sport is different than the most popular sport. While the popularity may change over the year the national sport most-likely never changes